414 LAKE SUPERIOR. 



shore, above which other and other terraces are seen ; six, ten, even 

 fifteen such terraces may be distinguished on one spot, forming, as it 

 were, the steps of a gigantic amphitheatre. The most remarkable of 

 all the amphitheatres has been sketched by Mr. Cabot, and forms the 

 frontispiece to this volume. Its height has been determined by Mr. 

 Logan, in his Geographical Report of Canada, page 10, where it is 

 minutely described. I therefore refer to this account for further de- 

 tails. I would only mention here, that the first shelf, within the reach 

 of the lake, consists of minute sand, and forms a narrow strip of sterile 

 ground along the water-edge ; next, we have a slope of about lO'^, fol- 

 lowed by a flat terrace, extending for nearly fifty paces to a seconl 

 very steep slope, about 26^ and 30° inclination ; then, a sloping ter- 

 race with an inclination of near 16°, stretching for eighty to a hundred 

 paces, above which rises another steep slope of 20°, beyond which 

 an extensive fiat, slightly sloping, extends for several hundred paces, 

 crowned by some irregular ridges at its summit, and along the rocky 

 ledges which form the bay at the bottom of which this high gravel 

 bank rises. 



In connection with these lake terraces, we must consider also the 

 river terraces which present similar phenomena along their banks all 

 around the lake, with the diSerence that they slope gradually along 

 the water courses, otherwise resembling in their composition the lake 

 terraces, which are altogether composed of remodeled glacial drift, 

 which, from the influence of the water and their having been rolled 

 on the shores, have lost, more or less, their scratches and polished ap- 

 pearance, and have assumed the dead smoothness of water pebbles. 

 Such terraces occur frequently between the islands, or cover low necks 

 connecting promontories with the main land, thus showing, on a small 

 scale, how by the accumulation of loose materials, isolated islands 

 may be combined to form larger ones, and how, in the course of time, 

 by the same process, islands may be connected with the main land. 



The lake shores present another series of interesting phenomena, 

 especially near the mouth of larger rivers emptying into the lake 

 over flats, where parallel walls of loose materials, driven by the action 

 of the lake against the mouth of the river, have successively stopped 

 its course and caused it to wind its way between the repeated accu- 

 mulations of such obstacles. 



